[Bug] extract-content.ts crashes on Windows: fs.cpSync aborts tsx with 0xC0000409

Problem

npm run dev in web/ never starts on Windows. The predev hook runs npm run extract, which uses tsx scripts/extract-content.ts. That script aborts partway through:

> [email protected] extract
> tsx scripts/extract-content.ts

Extracting course content...
  Repo root: <repo root>
  Source: root chapter folders (17)

...and then the process dies. No stack trace, no error message — just the shell prompt coming back with a non-zero exit code.

Root cause

copyChapterAssets() calls fs.cpSync(imagesDir, outDir, { recursive: true }):

https://github.com/shareAI-lab/learn-claude-code/blob/main/web/scripts/extract-content.ts#L218

On Windows with Node 22, fs.cpSync terminates the process at the native layer:

Exit code	3221226505 / 0xC0000409 (STATUS_STACK_BUFFER_OVERRUN)
JS exception	none — the process is killed before JS can catch anything

Because the failure is native, there is no stack trace to follow. This is why it looks like the script "hangs after Source: root chapter folders (17)".

Minimal reproduction

Reproducible outside this repo — copying a directory that contains a single one-line text file is enough:

const fs = require("fs");
fs.mkdirSync("src", { recursive: true });
fs.writeFileSync("src/a.txt", "x");
fs.cpSync("src", "dst", { recursive: true });  // process dies, exit 0xC0000409

$ node repro.js
$ echo $?
3221226505

Environment

OS	Windows 11
Node	v22.20.0
npm	(bundled with Node 22)

Impact

The extraction produces no web/public/course-assets/ output and no generated course data, so the web/ app cannot be built or run locally on Windows.

Possible fix

fs.cpSync is only used in this one place. Replacing it with a small recursive copy helper (fs.readdirSync + fs.mkdirSync + fs.copyFileSync) avoids the crashing native code path and keeps the behaviour identical:

before: exit 0xC0000409, extraction aborted, no course-assets output
after:  exit 0, "17 versions / 16 diffs / 51 docs", 74 asset files written

I have a patch ready and will open a PR that references this issue.

Note: opened with AI assistance for research/reproduction; I ran the reproduction and the fix on my own machine and stand behind the report.

中文说明（Chinese summary）

问题

在 Windows 上，web/ 下的 npm run dev 永远起不来。它的 predev 钩子会执行 npm run extract，也就是 tsx scripts/extract-content.ts。该脚本跑到一半就中断：

> [email protected] extract
> tsx scripts/extract-content.ts

Extracting course content...
  Repo root: <仓库根目录>
  Source: root chapter folders (17)

然后就没了 —— 没有堆栈、没有报错信息，只是 shell 提示符回来了，退出码非零。

根因

copyChapterAssets() 中调用了 fs.cpSync(imagesDir, outDir, { recursive: true })：

https://github.com/shareAI-lab/learn-claude-code/blob/main/web/scripts/extract-content.ts#L218

在 Windows + Node 22 下，fs.cpSync 会在原生层终止进程：

退出码	3221226505 / 0xC0000409（STATUS_STACK_BUFFER_OVERRUN）
JS 异常	无 —— 进程在 JS 能捕获任何东西之前就被杀掉了

正因为是原生层崩溃，所以没有任何堆栈可跟。这也是它看起来像「卡在 Source: root chapter folders (17)」的原因。

最小复现

脱离本仓库也能复现 —— 复制一个只含单行文本文件的目录就够了：

const fs = require("fs");
fs.mkdirSync("src", { recursive: true });
fs.writeFileSync("src/a.txt", "x");
fs.cpSync("src", "dst", { recursive: true });  // 进程死亡，退出码 0xC0000409

$ node repro.js
$ echo $?
3221226505

环境

操作系统	Windows 11
Node	v22.20.0

影响

提取过程不会生成任何 web/public/course-assets/ 产物，也不会生成课程数据，导致 web/ 应用在 Windows 上无法本地构建或运行。

可能的修复

fs.cpSync 全仓库只用了这一处。换成一个小型递归复制函数（fs.readdirSync + fs.mkdirSync + fs.copyFileSync）即可绕开会崩溃的原生代码路径，行为保持一致：

修复前：退出码 0xC0000409，提取中断，无 course-assets 产物
修复后：退出码 0，17 versions / 16 diffs / 51 docs，生成 74 个 asset 文件

补丁已就绪，我会开一个关联本 issue 的 PR。

说明：本 issue 借助 AI 完成调研与复现；复现过程与修复均由我本人在本机跑通，并认可该报告。